Mix together the brine ingredients and place your fish in a non-reactive container (plastic or glass), cover and put in the refrigerator.
Cure your salmon at least 4 hours, even for thin fillets from trout or pink salmon. Large trout or char, as well as pink, sockeye and silver salmon need 8 hours. A thick piece of king salmon might need as much as 36 hours in the brine. Never go more than 48 hours.
Take your fish out of the brine, rinse it briefly under cold running water, and pat it dry.
Set the fillets on your cooling rack, skin side down. Let the fish dry for 2 to 4 hours (or up to overnight in the fridge) to develop a shiny skin called a pellicle.
Start by slicking the skin of your fish with some oil, so it won't stick to the smoker rack.
Start the smoking process between 140°F and 150°F for up to an hour, then finish at 175°F for a final hour or two.
After an hour in the smoker, baste the fish with birch or maple syrup, or honey; do this every hour.
Your goal should be an internal temperature of about 130°F to 140°F.
Once your fish is smoked, let it rest on the cooling rack for an hour before you put it in the fridge.
